Saturday, April 24, 2010

Area Forecast Discussion - South Central/Southwest Missouri

FXUS63 KSGF 240519
NATIONAL WEATHER SERVICE SPRINGFIELD MO
1219 AM CDT SAT APR 24 2010

..MESOSCALE CONVECTIVE DISCUSSION...

..UPDATE TO AVIATION...

UPDATE...

00Z SUITE OF MESOSCALE MODELS ARE IN AND OUR SITUATION REMAINS
AS CLEAR AS MUD. BOTTOM LINE...THERE REMAINS A CONDITIONAL RISK
FOR SEVERE OVERNIGHT.

AT THE SFC...THE BOUNDARY EXTENDING FROM SE NEB THROUGH FAR E
KS/OK HAS MOVED VERY LITTLE OVER THE PAST FEW HOURS. TEMPERATURES
AHEAD OF THE BOUNDARY HAVE COOLED INTO THE LOW/MID 60S...RESULTING
IN AN INCREASE IN SFC AND ML CIN...TO THE TUNE OF AROUND -100
J/KG. SLIGHTLY LOWER VALUES OF ML CIN ARE NOTED TO THE SOUTHWEST
OF THE AREA...THOUGH THEY ARE STILL IN EXCESS OF -50 J/KG. THE
03Z KSGF RAOB CONFIRMS THE ABOVE VALUES AS A RATHER NICE CAP
AROUND THE 850MB LAYER RESULTS IN ML CIN OF -50 J/KG AND SFC BASED
CIN OF -87 J/KG.

THE UPPER LOW IS NOW CENTERED OVER WEST CENTRAL KS AT THIS
HOUR...WITH A MID LEVEL WAVE EMANATING FROM THIS FEATURE JUST NOW
ENTERING EASTERN KANSAS. CONVECTION HAS TRIED TO FIRE BEHIND THE
SFC BOUNDARY...THOUGH IT HAS HAD TROUBLE HOLDING TOGETHER. BETTER
HEIGHT FALLS FOCUSING ON NE KS/NW MO/SW IA HAVE RESULTED IN A MORE
ORGANIZED BRAND OF CONVECTION.

ALL TOLD...WE ARE JUST LACKING FORCING RIGHT NOW. INSTABILITY AHEAD
OF THE SFC BOUNDARY TO OUR WEST REMAINS MODEST...BUT PERSISTENT.
SBCAPE AND MLCAPE VALUES ARE STILL IN THE 500 TO 1000 J/KG RANGE
AS SFC DEWPOINTS CONTINUE TO POOL IN A NARROW CORRIDOR AHEAD OF
THE BOUNDARY. LOW LEVEL WINDS HAVE BACKED...RESULTING IN A SLIGHT
INCREASE IN LOW LEVEL CONVERGENCE ALONG THE SFC BOUNDARY...THUS ONE
CANNOT SAY THAT RISK FOR REDEVELOPING STORMS IS ZERO. IN FACT...
THE 00Z 4KM WRF-NMM FROM SPC INDICATES REDEVELOPMENT IN SE KS/NE
OK BY 08Z AND OUR LOCAL WRF-NMM DOES THE SAME.

GIVEN THE LOCATION OF FORCING MECHANISMS AT THIS JUNCTURE...SUCH
DEVELOPMENT SEEMS A TAD TOO QUICK. WILL NEED THE DIVERGENCE FROM
THE INCOMING RIGHT ENTRANCE REGION OF THE UPPER JET TO OUR
SOUTHWEST AND THE INFLUENCE OF THE MID LEVEL WAVE INCOMING FROM
OUR SOUTHWEST TO GARNER ENOUGH LIFT TO SUPPORT DEVELOPMENT ALONG
THE SFC BOUNDARY. EXPECTATIONS REMAIN THAT ANY REDEVELOPMENT WILL
BE LATE DURING THE OVERNIGHT...AFTER 4 AM.

SEVERE WEATHER RISKS ARE A LITTLE MORE MUDDLED NOW GIVEN OUR
INCREASING CAP. HAIL WOULD CONTINUE TO BE THE PRIMARY RISK...WITH
THE WIND AND TOR THREAT ON THE LOWER SIDE...THOUGH STILL NON ZERO.

GAGAN

&&

DISCUSSION...

..OVERVIEW...
MAIN FOCUS WITH THIS FORECAST PACKAGE WILL BE WITH THUNDERSTORMS
IN COVERAGE/INTENSITY THROUGH THE WEEKEND AS STRONG STORM SYSTEM
PUSHES ACROSS THE REGION.

..CURRENTLY...
SOME WIDELY SCATTERED/SCATTERED CONVECTION DEVELOPING OVER THE CWA
AS MLCAPES BETWEEN 700-1200 J/KG HAVE DEVELOPED WITH LITTLE OR NO
REMAINING CAP IN PLACE. SURFACE LOW STILL LOCATED IN THE CENTRAL
HIGH PLAINS WITH A WARM FRONT EXTENDING EAST SOUTHEAST DOWN
THROUGH CENTRAL MISSOURI. DEW POINTS HAVE RISEN INTO THE UPPER 50S
TO AROUND 60 ACROSS SOUTHERN MISSOURI WITH TEMPERATURES IN THE MID
70S. BACK EDGE OF MOISTURE AXIS WAS LOCATED JUST EAST OF WICHITA
TO CONCORDIA KANSAS LINE.

..FORECAST...
STORM SYSTEM WILL TRACK EAST TONIGHT INTO CENTRAL KANSAS WITH
MOISTURE AXIS SHIFTING EAST INTO SOUTHEAST MISSOURI. EXPECTING
CURRENT SCATTERED CONVECTION TO CONTINUE THROUGH THE EARLY EVENING
WITH BEST THUNDERSTORM COVERAGE GENERALLY SOUTH AND EAST OF A
BRANSON TO ROLLA LINE. ADDITIONAL LATE AFTERNOON DEVELOPMENT WILL
BE POSSIBLE AHEAD OF A DRY LINE DURING THE LATE AFTERNOON AND
EVENING WHICH WOULD PUSH INTO THE WESTERN PART OF THE CWA AFTER
00Z. AMOUNT OF INSTABILITY/SHEAR WILL ALLOW FOR THE POTENTIAL OF
ALL MODES OF SEVERE WEATHER TONIGHT. MOST OF THE PRECIPITATION
SHOULD SHIFT EAST OF THE AREA AFTER MIDNIGHT AS DRIER AIR MOVES IN
FROM THE WEST.

CONVECTION WILL AGAIN INCREASE ON SATURDAY AS THE COLD CORE UPPER
LOW MOVES ACROSS THE FORECAST AREA AND SURFACE LOW PUSHES ACROSS
NORTHERN ARKANSAS INTO THE BOOTHEEL REGION. STRONG SHEAR AND MID
LEVEL LAPSE RATES WILL BRING ANOTHER CHANCES OF SEVERE STORMS WITH
LARGE HAIL...DAMAGING WIND AND TORNADOES AGAIN ON SATURDAY...WITH
THE HIGHER RISKS ACROSS SOUTH CENTRAL MISSOURI.

THE UPPER LOW WILL TRACK TO THE NORTHEAST OF THE AREA SATURDAY
NIGHT INTO SUNDAY WITH CYCLONIC FLOW BRINGING MORE SHORTWAVE
ENERGY INTO THE REGION. HAVE INCLUDED SCATTERED
CONVECTION...MAINLY FOR THE NORTHEAST CWA ON SUNDAY.

WEST TO NORTHWEST FLOW WILL CONTINUE THROUGH TUESDAY OF
THE UPCOMING WORK WEEK. AN UPPER RIDGE WILL THEN BUILD INTO THE
REGION BEFORE THE NEXT STRONG WAVE MOVES IN THURSDAY NIGHT INTO
FRIDAY.

LINDENBERG

&&

AVIATION...

FOR THE 06Z TAFS...PRIMARY FORECAST CHALLENGE CONTINUES TO BE
TIMING ANY TSRA...WITH AN INCREASE CONCERN FOR IFR CIGS AT BBG/SGF
FOR THE NEXT FEW HOURS. IFR CIGS WILL CONTINUE UNTIL MID/UPPER
CLOUDS INCREASE FROM THE SW. THE RISK FOR TSRA DEVELOPMENT WILL
INCREASE AFTER 09Z AT ALL TAF SITES...THOUGH THE WINDOW OF
OPPORTUNITY IS PRETTY SMALL AT JLN AS THE SFC FRONT IS EXPECTED TO
BE THROUGH THIS AERODROME AROUND SUNRISE. THE RISK FOR TSRA WILL
PERSIST INTO SATURDAY AT SGF/BBG IN PERIODIC BOUTS. THE FIRST
BEING PRIOR TO SUNRISE...THE SECOND TOWARDS THE EARLY AFTERNOON
HOURS OF SATURDAY.

GAGAN

&&

SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$

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